1. Field of the Invention
The invention relates to a method for moving a double-bladed rotor of a wind power plant into a parking position.
2. Discussion of the Prior Art
Transferring wind power plants from an operating position into a parking position is always necessary when climatic conditions, in particular high wind loads, occur, that may damage the wind power plants on account of the immense forces that partly act only briefly on the wind power plants. Thus wind power plants are vulnerable in particular in regions with a high occurrence rate of extreme winds, in particular seasonally occurring winds and whirlwinds such as hurricanes or typhoons that also exhibit a high degree of turbulence.
In particular three-bladed rotors are affected especially by cross flows due to the geometric arrangement of the blades, that could lead to extremely high loads and finally to the destruction of the plant. To dimension the wind power plant components such that they can withstand these forces seems impossible for these cases.
So that wind power plants can be installed even in these regions and their potential to extract energy can be used, several mechanisms have already been developed for protecting the wind power plants from damage by the storms that have been mentioned.
EP 0 709 571 A2 thus introduces a wind power plant with a double-bladed rotor that has rotor blades with rotor blade sections that can be rotated freely relative to each other, so that on the one hand the entire rotor can be oriented parallel to the wind direction or in the case of a frontal flow at least the load acting on the rotor can be reduced.
A disadvantage of this design is however the very complex blade structure that is complicated and is likewise susceptible for high wind loads.
In contrast, DE 101 41 098 A1 totally dispenses with braking and locking the rotor. There the rotor is to be stabilized without braking and without locking in a rotating position by preventing the rotor from leaving the parking position on account of turbulences by adjusting the rotor blades into a position that counteracts the rotational movement. The control is to effect an “idling” of the rotor in this way without leaving the parking position.
However, it seems doubtful that the control introduced in DE 101 41 098 A1 without further details can react with such a speed to turbulences that the wind power plant having this type of control can avoid damage by high wind loads. Rather it has to be expected that the components of the wind power plant that move while high wind loads occur generate further variable moments that would have to be taken into account when designing and dimensioning the components. The construction of such wind power plants can however hardly be calculated because the parameters cannot be predetermined.